This invention relates to a liquid containment device with a self-contained pump for dispensing liquid in small doses of a predetermined volume. More particularly, this invention relates to a replaceable containment device of the foregoing character which is useful in an ink-jet printer for containing a supply of printing ink and for dispensing the printing ink to a printing head upon the actuation of the self-contained pump.
A pending U.S. patent application filed by Bruce Cowger and Norman Pawlowski, Jr., for an invention entitled xe2x80x9cInk Supply For An Ink-Jet Printer,xe2x80x9d describes an ink supply for an ink-jet printer that is separate from the printer ink pen, and can be replaced upon the emptying of the ink supply without the need to replace the printer ink pen. The ink supply of the aforesaid U.S. patent application incorporates a self-contained pumping device for dispensing ink from a pumping chamber, and describes, as an embodiment of such a pumping device, a bellows pump. However, a bellows pump requires a relatively large extended surface of a semi-rigid material, such as a polymeric material, and is subject to a relatively high rate of oxygen and moisture transfer through the material of the bellows. This oxygen and/or moisture transfer can result in the degradation of the ink within the ink supply, especially in a printer that is used only infrequently. Further, the bellows is subject to leakage at the location of its attachment to another portion of the ink supply. According to the aforesaid pending U.S. patent application Ser. No. 08/429,987, these and other problems associated with the use of a bellows can be avoided by the use of a pumping device having a rigid perimetrical wall, preferably formed integrally with the associated chassis structure of the ink supply, with a linearly acting pumping member that is moveable within a pumping chamber defined by the rigid wall to pressurize ink within the pumping chamber, and a flexible moisture and oxygen barrier film heat sealed to an edge of the perimetrical wall in a continuous pattern and overlying the pumping member.
An ink supply according to the aforesaid U.S. patent application Ser. No. 08/429,987 incorporates a check valve in the form of a thin, flexible flapper valve heat staked to the chassis to prevent the return of ink from the pumping chamber to the pouch upon the pressurization of the ink during a dispensing cycle. However, the heating of the flapper valve needed to heat stake the flapper valve to the chassis can result in permanent distortion of the flapper valve, with a resultant loss in effectiveness of its flow retarding qualities during ink dispensing cycles. It has now been found, however, in accordance with certain embodiments of the present invention that a suitable check valve in the form of a flapper valve can be provided without the need to heat stake the flapper valve to the chassis by providing a spring to urge the flapper valve against the chassis, either in the form of a spring that is aligned with the opening in the chassis that is to be closed by the flapper valve or a spring that is offset with respect to such opening. It has also been found, in accordance with an alternative embodiment of the present invention, that a suitable check valve can be provided in the form of a spring biased or free-floating check ball that selectively seats against a fixed seat to block the return of ink from the pumping chamber to the pouch during a pumping cycle while permitting ink flow from the pouch into the pumping chamber at the conclusion of a pumping cycle.
Accordingly, it is an object of the present invention to provide an improved liquid containing and dispensing device. It is also a corollary object of the present invention to provide an improved device of the foregoing character that is useful in containing and dispensing ink in an ink-jet printer.
More particularly, it is an object of the present invention to provide a liquid containment and dispensing device with an improved check valve to prevent the return of liquid from a pumping element of the device to a liquid containing pouch during a pumping cycle and it is a corollary object of the present invention to provide a device of the foregoing character that is useful in containing and dispensing ink in an ink-jet printer.
For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the preferred embodiment of the invention, and to the appended claims.